The present invention relates generally to the field of assembly of heat exchangers, and more particularly to heat exchangers of a flat shape. However, certain applications may be outside of this field.
Heat exchangers are used in many applications where heat is rejected from a source and absorbed by a sink. For example, automobiles, trucks and buses utilize heat exchangers to reject heat from the engine, air conditioning, and transmission, and also to have heat absorbed by the passenger compartment. The heat exchangers are sometimes configured as an alternating array of tubes and fins. Headers, or collectors, unite the tubes in fluid communication. These heat exchangers may be substantially planar.
To keep the cost of these heat exchangers low, it is necessary to automate certain aspects of their construction. In one example of such automation, a machine utilizes a translating platform to dispense flattened tubes in a substantially downward direction onto positions on a receiving fixture. A motor drives both the platform and a dispenser attached to the platform by a combination of mechanical links such as rack and pinion gears and chains and sprockets. The action of the dispenser to eject tubes is mechanically linked to translation of the platform across the receiving fixture. For example, relatively slow translation of the platform results in relatively slow ejection of tubes. Also, the positions at which tubes are deposited is determined by the mechanical linkage. Changing the predetermined positions of the tubes on the receiving fixture requires changing the mechanical linkage.
A drawback of this machine is in the time and cost required to change the predetermined positions at which the tubes are ejected onto the receiving fixture, also known as the pitch of the tubes. A gearset of the machine must be changed, which requires a partial teardown of the machine, with subsequent rebuild and realignment. Another drawback of this machine is the difficulty encountered in speeding up the machine to increase throughput of assembled heat exchangers. As the machine speed of translation is increased, the velocity with which the tubes are ejected increases. With high ejection velocity, the tubes bounce out of location on the receiving fixture, requiring attention from the human operator before assembly can be resumed.
There are other examples of machines and methods for assembling heat exchangers. Some of this related art can be found in the following U.S. Pat. Nos.:
______________________________________ Patent No. Patentee ______________________________________ 4,637,132 wase et al. Iwase et al. 4,486,933 Breda et al. 4,900,328 Breda et al. 5,029,382 Breda et al. 4,860,421 Beddome et al. 5,226,234 Barnard 4,228,573 Kiesche et al. 4,873,753 McKinney 4,901,416 Ochiai et al. 4,898,232 Sasaki 5,562,153 Chester 4,180,897 Alvarez et al. 5,479,707 Martin et al. 4,321,739 ______________________________________
What is needed is an improved method and apparatus for assembling heat exchangers.